DESCRIPTION: The objective of this proposal is to develop electrochemical biosensors capable of providing continuous real-time therapeutic drug monitoring with unprecedented chemical specificity and temporal resolution. The ability to provide real-time information about an individual's response to therapeutics has the potential to revolutionize healthcare by offering personalized treatment. Drugs with narrow therapeutic windows become toxic or ineffective if over- or under-dosed. Maintaining the most efficient dosage, personalized to the patient, can reduce toxicity, maximize efficacy of treatment, and ultimately improve patient outcome. Unfortunately, current methodologies for monitoring therapeutics are cumbersome (requiring tens of minutes to hours) and are performed removed from the point of care precluding real-time feedback. Biosensors represent a promising alternative but often fail to respond to specific targets when challenged in biological sample matrices. This failure is a result of biofouling, which masks the true sensor response. Here, we aim to leverage state-of-the-art bioanalytical science with biocompatible material (hydrogel) engineering to develop hybrid sensors capable of real-time continuous therapeutic drug monitoring in vivo. The specific goal is to couple the biocompatibility of hydrogel membranes with the rapid, selective, and specific recognition capabilities of electrochemical, aptamer-based (E-AB) sensors. The aims of the proposal are to first establish fundamental and universal sensor design and biomaterial engineering guidelines followed by the translation of the sensor to commercially engineered in vivo probes for multi- analyte detection. The short-term goal is to develop sensors for the real-time monitoring of the antibiotic tobramycin used for treatment of cystic fibrosis pulmonary exacerbations. In the long-term, combining the sensor development expertise of the PI and the biomaterial engineering expertise of the Co-PI, the general sensors developed here will be adapted to interface with a variety of biological interfaces including tissue and neuronal systems.